Liquid crystal display and electronic apparatus having electrodes with openings therein

ABSTRACT

A liquid crystal device includes a pair of substrates composed of an element substrate and a counter substrate and a liquid crystal layer that is held between the pair of substrates. In the liquid crystal device, a data line and a scanning line are provided on the element substrate in a manner to be orthogonal to each other, a plurality of pixels including a switching element are arranged in matrix, a first electrode and a second electrode are provided on the element substrate, an image signal potential is supplied to the first electrode via the switching element, a common potential is supplied to the second electrode, the second electrode includes a plurality of openings, and a width, in an alignment direction of the plurality of openings, of the opening positioned on an outermost side in the alignment direction is smaller than a width of the rest of the openings.

CROSS REFERENCES TO RELATED APPLICATIONS

The present application contains subject matter related to thatdisclosed in Japanese Priority Patent Application JP 2009-089792 filedin the Japan Patent Office on Apr. 2, 2009, the entire contents of whichare hereby incorporated by reference.

BACKGROUND

The present application relates to a liquid crystal device and anelectronic apparatus.

Examples of liquid crystal display devices employing a lateral electricfield mode include an in-plane switching (IPS) mode liquid crystaldisplay device, a fringe field switching (FFS) mode liquid crystaldisplay device, and the like. In the IPS mode liquid crystal displaydevice, a pixel electrode and a common electrode which generate alateral electric field are formed on the same layer and an electricfield (that is, a lateral electric field) is generated in a liquidcrystal layer in an approximately parallel direction to a substratesurface. Accordingly, visibility in the IPS mode liquid crystal displaydevice can be advantageously improved compared to a twisted nematic (TN)mode liquid crystal display device which is one of liquid crystaldisplay devices of a vertical electric field mode. However, there is adisadvantage that it is difficult to sufficiently drive liquid crystalmolecules positioned directly on the pixel electrode, causingdegradation of light transmission.

On the other hand, in the FFS mode liquid crystal display device, apixel electrode and a common electrode are formed on different layerswith an insulation layer interposed and thus a direction of an electricfield generated in a liquid crystal layer is different from that of theIPS mode liquid crystal display device. Therefore, the electric field isapplied to liquid crystal molecules positioned directly on the pixelelectrode as well and thereby the liquid crystal molecules on this partcan be sufficiently driven. As a result, light transmission can beadvantageously improved in the FFS mode liquid crystal display devicemore than the IPS mode liquid crystal display device described above.Especially, Japanese Unexamined Patent Application Publication No.2007-226175 discloses a liquid crystal device in which an insulationfilm for planarization is formed on a lower layer side of two electrodeswhich generate a lateral electric field in the FFS mode. Further, anelectrode provided on an upper layer side has a shape including aplurality of long and thin openings (slits) in the FFS mode liquidcrystal device. Japanese Unexamined Patent Application Publication No.2008-116484 discloses a liquid crystal device in which a relationshipbetween the width on an electrode portion positioned between openingsand the width of the openings are optimized so as to improve displayquality.

SUMMARY

In Japanese Unexamined Patent Application Publication No. 2008-116484,for example, the most preferable dimensions of the width of theelectrode portion and the width of the opening are obtained from arelationship between a driving voltage and the maximum transmittance.However, the inventor found that unevenness in brightness arose in apixel even if these dimensions were merely optimized. The unevenness inbrightness in a pixel eventually results in degradation of lighttransmittance. Therefore, in the configuration of the related art, aproperty, in which light transmittance can be improved and brighterdisplay can be obtained, of one of properties of the FFS mode could nothave been sufficiently utilized.

It is desirable to provide a liquid crystal device in which evenness inbrightness in a pixel can be realized and light transmittance isimproved so as to be able to obtain bright display, and an electronicapparatus provided with the liquid crystal device.

According to an embodiment, there is provided a liquid crystal deviceincluding a pair of substrates composed of an element substrate and acounter substrate, and a liquid crystal layer that is held between thepair of substrates. In the liquid crystal device, a data line and ascanning line are provided on the element substrate in a manner to beorthogonal to each other, a plurality of pixels including a switchingelement that is electrically connected to the data line and the scanningline are arranged in matrix, a first electrode and a second electrodethat applies an electric field generated between the second electrodeand the first electrode to the liquid crystal layer are provided on theelement substrate, an image signal potential from the data line issupplied to the first electrode via the switching element, a commonpotential is supplied to the second electrode, the second electrodeincludes a plurality of openings that extend in directions parallel witheach other, and among the plurality of openings, a width, in analignment direction of the plurality of openings, of the openingpositioned on an outermost side in the alignment direction is smallerthan a width, in the alignment direction, of the rest of the openings.

The liquid crystal device according to the embodiment is so-called anFFS mode liquid crystal device which is provided with the firstelectrode and the second electrode that applies an electric fieldgenerated between the second electrode and the first electrode to theliquid crystal layer, on the element substrate thereof. The inventorfound that in a case of an FFS mode liquid crystal device of the relatedart in which the widths of a plurality of openings of a second electrode(upper layer side electrode) are same as each other, a lateral electricfield component was more intensely generated in an edge part of theopening positioned on the outermost side than other part and lighttransmittance in the outermost part was increased to be unbalanced withrespect to other part, causing unevenness in brightness. Then, theinventor found that evenness of transmittance with respect to other partwas improved and unevenness of brightness in a pixel could be reduced bysetting the width, in the alignment direction, of the opening positionedon the outermost side to be smaller than the width, in the alignmentdirection, of other openings. Details will be described later.

In the liquid crystal device according to the embodiment, it ispreferable that when the width, in the alignment direction, of theopening positioned on the outermost side is set to be S1 [μm] and thewidth, in the alignment direction, of the rest of the openings is set tobe S2 [μm], S2−S1≧0.5 be satisfied.

This configuration enables stable manufacturing in an actualmanufacturing process and can securely provide advantageous effects ofthe embodiment.

According to another embodiment, there is provided a liquid crystaldevice including a pair of substrates composed of an element substrateand a counter substrate, and a liquid crystal layer that is held betweenthe pair of substrates. In the liquid crystal device, a data line and ascanning line are provided on the element substrate in a manner to beorthogonal to each other, a plurality of pixels including a switchingelement that is electrically connected to the data line and the scanningline are arranged in matrix, a first electrode and a second electrodethat applies an electric field generated between the second electrodeand the first electrode to the liquid crystal layer are provided on theelement substrate, a common potential is supplied to the firstelectrode, an image signal potential from the data line is supplied tothe second electrode via the switching element, the second electrodeincludes a plurality of openings that extend in directions parallel witheach other, and among a plurality of electrode parts adjacent to theopenings, a width, in an alignment direction of the plurality ofelectrode parts, of the electrode part positioned on an outermost sidein the alignment direction is smaller than a width, in the alignmentdirection, of the rest of the electrode parts.

In the liquid crystal device according to the other embodiment, apositional relationship of an electrode (that is, a pixel electrode), towhich an image signal potential from the data line is supplied, and anelectrode (that is, a common electrode), to which a common potential issupplied, with the insulation film interposed is opposite to therelationship in the liquid crystal device of the embodiment describedfirst. In the liquid crystal device of the embodiment described first inwhich the common electrode is disposed on the upper layer side and thepixel electrode is disposed on the lower layer side, an advantageouseffect of the embodiment is described by using “the width of theopening”. In the liquid crystal device of the other embodiment in whichthe pixel electrode is disposed on the upper layer side and the commonelectrode is disposed on the lower layer side, it is conceivable that“the width of the electrode part” is equivalent to “the width of theopening” in the liquid crystal device of the embodiment described first.Accordingly, in the liquid crystal device of the other embodiment,unevenness of brightness in a pixel can be reduced by setting the widthof the electrode part positioned on the outermost side to be smallerthan the width of the rest of the electrode parts.

In the liquid crystal device according to the embodiment, it ispreferable that when the width, in the alignment direction, of theelectrode part positioned on the outermost side is set to be L1 [μm] andthe width, in the alignment direction, of the rest of the electrodeparts is set to be L2 [μm], L2−L1≧0.5 be satisfied.

This configuration enables stable manufacturing in an actualmanufacturing process and can securely provide advantageous effects ofthe embodiment.

According to still another embodiment, there is provided an electronicapparatus including the liquid crystal device of the embodimentsdescribed above as a display unit.

According to the embodiment, the electronic apparatus includes theliquid crystal device of the embodiments described above, so that theelectronic apparatus including a bright liquid crystal display unit canbe provided.

Additional features and advantages are described herein, and will beapparent from the following Detailed Description and the figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a plan view showing a liquid crystal device according to anembodiment;

FIG. 2 is a sectional view taken along II-II line of FIG. 1;

FIG. 3 is an equivalent circuit diagram of the liquid crystal device;

FIG. 4 is a plan view of a pixel constituting a display unit of theliquid crystal device;

FIG. 5 is a sectional view taken along V-V line of FIG. 4;

FIG. 6 is a plan view showing a part of a common electrode correspondingto one pixel;

FIG. 7 illustrates equipotential lines and distribution of lighttransmittance in electric field applying in an FFS system;

FIG. 8 illustrates a state that light transmittance is changed when awidth of openings on both ends is changed;

FIG. 9 is a graph showing a relationship between the width of theopenings on the both ends and the maximum luminance;

FIG. 10 illustrates a state that light transmittance is changed whenconditions (width of openings, width of electrode parts) are changedfrom the state in FIG. 8;

FIG. 11 is a graph showing a relationship between the width of theopenings on both ends and the maximum luminance while corresponding tothe state of FIG. 10;

FIG. 12 is a plan view showing a pixel constituting a display unit of aliquid crystal device according to another embodiment;

FIG. 13 is a sectional view taken along XIII-XIII line of FIG. 12; and

FIG. 14 is a perspective view showing an electronic apparatus of stillanother embodiment.

DETAILED DESCRIPTION

Embodiments of the present application will be described below in detailwith reference to the drawings.

An embodiment will be described with reference to FIGS. 1 to 11.

A liquid crystal device according to the embodiment is an example of atransmission type liquid crystal display device of the FFS mode.

In FIGS. 1 to 11, scales of respective layers and respective members areadequately changed in the extent that they can be recognized in thedrawings.

As shown in FIGS. 1 and 2, in a liquid crystal device 1 according to theembodiment, a thin film transistor (abbreviated below as a TFT) arraysubstrate 2 and a counter substrate 3 are bonded to each other by asealing member 4 and a liquid crystal layer 5 is sealed in a regionpartitioned by the sealing member 4. The liquid crystal layer 5 is madeof a liquid crystal material having positive dielectric anisotropy. In aregion in the inside of a forming region of the sealing member 4, alight shielding film (a peripheral break line) 6 which is made of alight shielding material is formed. In a peripheral circuit region onthe outside of the sealing member 4, a data line driving circuit 7 andan external circuit mounting terminal 8 are formed along one side of theTFT array substrate 2, and scanning line driving circuits 9 are formedrespectively along two sides which are adjacent to the above-mentionedone side. On the rest side of the TFT array substrate 2, a plurality ofwirings 10 for connecting the scanning line driving circuits 9 formed onboth sides of a display region R are provided. On corners of the countersubstrate 3, inter-substrate conducting members 11 for electricallyconducting the TFT array substrate 2 and the counter substrate 3 areprovided.

A horizontal direction of the display region R is expressed by an arrowH and a vertical direction of the display region R is expressed by anarrow V. The horizontal direction H is a direction along one side (aside in a lateral direction in FIG. 1) of the display region R having arectangular shape and the vertical direction V is a direction along oneside (a side in a longitudinal direction in FIG. 1) adjacent to the oneside.

In a plurality of pixels which are arranged in matrix so as toconstitute the display region of the liquid crystal device 1 of theembodiment, pixel electrodes 13 are respectively formed, as shown inFIG. 3. Further, on a lateral side of the pixel electrode 13, a TFT 14which is a pixel switching element for performing conduction control tothis pixel electrode 13 is formed. To sources of the TFTs 14, data lines15 are electrically connected. To the data lines 15, image signals S1,S2, . . . , Sn are respectively supplied. The image signals S1, S2, . .. , Sn may be supplied to respective data lines 15 in a line order asthis order or may be supplied to the plurality of data lines 15 whichare adjacent to each other, in a group unit.

Further, to gates of the TFTs 14, scanning lines 16 are electricallyconnected. To the scanning lines 16, scanning signals G1, G2, . . . , Gmare respectively supplied in a pulse mode at predetermined timing. Here,the scanning signals G1, G2, . . . , Gm are applied to respectivescanning lines 16 in a line order as this order. To drains of the TFTs14, the pixel electrodes 13 are electrically connected. When certainTFTs 14 which are switching elements are turned on in a predeterminedperiod of time by the scanning signals G1, G2, . . . , Gm which aresupplied from the scanning lines 16, the image signals S1, S2, . . . ,Sn which are supplied from the data lines 15 are written in liquidcrystal of respective pixels through the TFTs 14 at predeterminedtiming.

The image signals S1, S2, . . . , Sn which are written in the liquidcrystal and have a predetermined level are held in liquid crystalcapacitors which are formed between the pixel electrodes 13 and a commonelectrode to which a common potential is applied, in a predeterminedperiod of time. Here, in order to prevent a leak of the image signalsS1, S2, . . . , Sn which are held, a storage capacitor 18 is formedbetween the pixel electrode 13 and a capacity wiring 17 so as to bedisposed in parallel with the liquid crystal capacitor. Thus, if avoltage signal is applied to the liquid crystal, an alignment state ofthe liquid crystal molecules is changed depending on a level of avoltage which is applied. Accordingly, light incident on the liquidcrystal is modulated and gradation display is performed.

The pixel configuration of the liquid crystal device 1 of the embodimentis now described with reference to FIGS. 4 and 5.

In the liquid crystal device 1 of the embodiment, one pixel constitutingan image is composed of three pieces of sub pixels of red (R), green(G), and blue (B). Here, FIG. 4 shows four pieces of sub pixelsincluding two sub pixels aligned in an extending direction of the dataline 15 (vertical direction of FIG. 4) and two sub pixels aligned in anextending direction of the scanning line 16 (horizontal direction inFIG. 4). Here, an electrode allocated for each sub pixel is called a“pixel electrode” in this specification, so that a part whichprincipally corresponds to a “sub pixel” is sometimes called a “pixel”depending on configuration elements.

The planar configuration of each sub pixel is first described.

As shown in FIG. 4, a plurality of data lines 15 are disposed with apredetermined interval, and a plurality of scanning lines 16 aredisposed with a predetermined interval so as to be orthogonal to thedata lines 15, on the TFT array substrate 2. A region surrounded byadjacent two data lines 15 and adjacent two scanning lines 16 is a subpixel region. On a corner of each sub pixel region (a corner on thelower left of each sub pixel region in FIG. 4), the TFT 14 is disposed.The TFT 14 of the embodiment is a low-temperature poly-Si TFT includinga semiconductor layer 20 made of polycrystalline silicon which is formedin a low-temperature process, for example. On the semiconductor layer20, a part protruded from the data line 15 which functions as a sourceelectrode and a drain electrode 25 are disposed so as to be partiallysuperposed to each other.

In the embodiment, a common potential is supplied to a common electrodein all sub pixels, so that a solid-type common electrode covering allsub pixels is provided. Here, the common electrode may be provided in adivided manner for every sub pixel. As described later, the pixelelectrode 13 is disposed on a lower layer side and a common electrode 21is disposed on an upper layer side. In the inside of each sub pixelregion, the pixel electrode 13 having an approximate rectangular shapeis provided. On the common electrode 21 inside each sub pixel region, aplurality of openings 23 a and 23 b which extend in approximatelyparallel with the extending direction of the data line are formed. Areference numeral 25 denotes a drain electrode for connecting a drainregion of the semiconductor layer and the pixel electrode, and areference numeral 26 denotes a drain contact hole.

The sectional configuration is now described.

As shown in FIG. 5, in the TFT array substrate 2, the scanning line 16is formed on an upper surface of a substrate body 33 which is made ofglass or the like and a part, which is below a channel region of thesemiconductor layer 20, of the scanning line 16 functions as a gateelectrode as it is. A gate insulation film 34 which is made of asilicone oxide film or the like, for example, is formed on the wholesurface of the substrate body 33 so as to cover the scanning line 16.The semiconductor layer 20 is formed on a part of the gate insulationfilm 34, and the data line 15 is formed so as to contact with a sourceregion of the semiconductor layer 20. A part of the data line 15, shownin FIG. 4, which is protruded in a manner to be superposed on thesemiconductor layer 20 in a plane fashion functions as a sourceelectrode. The drain electrode 25 is formed to contact with a drainregion of the semiconductor layer 20. A first interlayer insulation film35 which is made of a silicon oxide film, for example, is formed on thewhole surface of the gate insulation film 34 so as to cover theseconfiguration elements of the TFT 14.

The pixel electrode 13 is formed on the first interlayer insulation film35 and is electrically connected with the drain electrode 25 through thedrain contact hole 26 which penetrates the first interlayer insulationfilm 35. Due to this configuration, the pixel electrode 13 iselectrically connected with the drain region of the semiconductor layer20 of the TFT 14 through the drain electrode 25. A second interlayerinsulation film 36 which is made of a silicon oxide film, a siliconnitride film, or the like, for example, is formed on the whole surfaceof the first interlayer insulation film 35 so as to cover the pixelelectrode 13. On the second interlayer insulation film 36, the commonelectrode 21 is formed. On the common electrode 21, an alignment film(not shown) on which rubbing processing is performed is formed.

On the other hand, in the counter substrate 3, coloring layers 41 of R,G, and B which constitute a color filter are formed on a lower surfaceof a substrate body 40 which is made of glass or the like, and a blackmatrix BM (light shielding layer) is formed on a region overlapping withthe TFT 14, the data line 15, the scanning line 16, and the like. Anovercoat layer 42 which serves as a protection film of the color filteris formed to cover the coloring layers 41 and the black matrix BM, andan alignment film (not shown) on which rubbing processing is performedis formed on the overcoat layer 42.

A liquid crystal layer 5 is sandwiched and held between the TFT arraysubstrate 2 and the counter substrate 3 described above. On outersurface sides of the TFT array substrate 2 and the counter substrate 3,polarization plates 44 and 45 are respectively formed. Outside thepolarization plate 44 disposed on the TFT array substrate 2 side, a backlight 46 (illuminating device) is provided.

FIG. 6 is a plan view showing a part of the common electrode 21corresponding to one sub pixel. The TFT 14 is not shown in FIG. 6. Asdescribed above, a plurality of long and thin openings 23 a and 23 b areformed in the common electrode 21 in each sub pixel region in theextending direction of the scanning line 16 with the predeterminedinterval. Further, each of the openings 23 a and 23 b extends inapproximately parallel with the extending direction of the data line 15,and the plurality of openings 23 a and 23 b are arranged so as to beapproximately parallel with each other. Among the plurality of openings23 a and 23 b, the width (dimension in a short-side direction) of theopening 23 a which is positioned on the outermost side in the alignmentdirection of the openings (the extending direction of the scanning line16) is set to be smaller than the width (dimension in a short-sidedirection) of the alignment direction of the openings 23 b other thanthe opening 23 a. Hereinafter, “the width in the alignment direction ofthe openings (or electrode parts)” is referred to as merely “the widthof the openings (or the electrode parts)”.

In this embodiment, when the width of the opening 23 a positioned on theoutermost side is set to be S1 [μm] and the width of the openings 23 bother than the opening 23 a is set to be S2 [μm], S2−S1≦0.5 issatisfied. Specifically, the width S1 of the opening 23 a positioned onthe outermost part is 4 μm and the width S2 of the openings 23 b otherthan the opening 23 a is 4.5 μm, for example. Further, the width L ofthe electrode part 21 a positioned between adjacent two openings 23 aand 23 b is 3.5 μm.

In the FFS mode liquid crystal device, regions in which potential changeis large are concentrated on the TFT array substrate side compared tothe counter substrate side in the liquid crystal layer. This isdifferent from the IPS mode liquid crystal device even though both ofthese liquid crystal devices employ the mode in which liquid crystal isdriven by a lateral electric field. The upper and lower asymmetricproperty of this potential distribution is considered in optimization ofparameters such as a pitch of an opening (slit) of the second electrode(upper layer side electrode), the thickness of a dielectric film betweenthe second electrode and the first electrode (lower layer sideelectrode), the thickness of the liquid crystal layer, and the thicknessof the alignment film provided on the second electrode. However, theinventor focused attention on a point that there also was acharacteristic, which was not exhibited in the IPS mode liquid crystaldevice and had not been taken into consideration in the related art, inpotential distribution around the opening which was positioned on theoutermost part of a sub pixel.

Therefore, the inventor obtained potential distribution in a liquidcrystal layer and transmittance distribution in the FFS mode electrodeconfiguration through simulation. The simulation result is shown in FIG.7. In FIG. 7, an equipotential line is expressed by a dashed-dotted lineand transmittance distribution is expressed by a solid line. A referencecharacter 51 denotes a first electrode, reference characters 52 a and 52b denote second electrodes, and a reference character 53 denotes adielectric body. In the embodiment, the first electrode 51 correspondsto the pixel electrode 13, the second electrodes 52 a and 52 bcorrespond to the common electrodes 21 a and 21 b, and the dielectricbody 53 corresponds to a third interlayer insulation film 37. A partdenoted by a reference character 54 a is the opening positioned on theoutermost part of the sub pixel, and a part on the right side of theopening 54 a is a part 52 b in which the second electrode long extends.Further, in this simulation, the widths of all of openings 54 a and 54 bwere set to be equal to each other.

From the result of FIG. 7, it is understood that equipotential linesshow approximately same shapes on the center side of the sub pixel (leftside from the center of FIG. 7), while equipotential lines rapidly standup in the longitudinal direction near an outer edge of the opening 54 apositioned on the outermost part and thus a lateral electric fieldcomponent is strong. In the lateral electric field mode, as the lateralelectric field component becomes strong, the light transmittance tendsto become higher. Therefore, the light transmittance changes inapproximately constant cycle on the central side of the sub pixel, butthe light transmittance exhibits a high peak near the outer edge of theopening 54 a positioned on the outermost part. Accordingly, it wasunderstood that when the widths of the openings were set to be equal toeach other, brightness became uneven in the sub pixel as thissimulation. The unevenness of the brightness show that even if a voltageapplied to the liquid crystal layer is changed, it is difficult toadjust the brightness and therefore bright display is not obtained.Accordingly, the inventor conceived that the width of the openingpositioned on the outermost part was set to be smaller than that ofother openings.

FIG. 8 illustrates a simulation result showing transmittancedistribution on each position in the sub pixel. In FIG. 8, a horizontalaxis indicates a position [μm] in the sub pixel and a vertical axisindicates transmittance [%]. A graph expressed by a solid line indicatestransmittance distribution in the liquid crystal device of theembodiment in which the width S1 of the opening positioned on theoutermost part is 4 μm, the width S2 of the rest of the openings is 4.5μm, and the width L of the electrode parts is 3.5 μm. A graph expressedby a dotted line indicates transmittance distribution in a liquidcrystal device of a comparison example in which the width S of allopenings is 4.5 μm and the width L of electrode parts is 3.5 μm. Here,in this simulation, a voltage applied to the liquid crystal layer wasset to be a constant halftone voltage.

In the case of the comparison example, a peak showing the maximumtransmittance is higher in the outermost part than that in the centralpart, and thus brightness increases faster in the outermost part eventhough the same voltage is applied. In contrast, in the case of theembodiment, it was understood that the height of a peak in the outermostpart became close to the height of a peak in the central part becausethe width S1 of the opening positioned on the outermost part wasdecreased to be 4 μm, and thus even transmittance distribution could beobtained over the entire region.

In the simulation shown in FIG. 8, the voltage applied to the liquidcrystal layer was set to be constant. On the other hand, in FIG. 9, themaximum luminance (the maximum transmittance) in each width of theopenings was obtained by changing an applied voltage. The horizontalaxis of FIG. 9 indicates the width [μm] of the opening and the verticalaxis indicates the maximum luminance [relative value]. The maximumluminance indicated by the vertical axis is expressed by a relativevalue which is obtained in a condition that the maximum luminance is setto be 1 in a comparison example in which the width S of all openings isset to be 4.5 μm.

It was understood that the maximum luminance could be improved bysetting the width of the opening positioned on the outermost part to besmaller than that of other openings such that the opening positioned onthe outermost part was 4 μm and the width of other openings was 3.5 μm.

The widths of the electrode parts and the openings are commonly set tobe 2 μm to 6 μm, but the above-described result does not depend on thewidth of the electrode parts or the openings at least in this range.

FIG. 10 illustrates a simulation result showing transmittancedistribution when the width S of the opening was set to be 4 μm and thewidth L of the electrode part was set to be 3 μm. A graph expressed by asolid line indicates transmittance distribution obtained when the widthS1 of the opening positioned on the outermost part was 3.5 μm and thewidth S2 of the rest of the openings was 4 μm. A graph expressed by adotted line indicates transmittance distribution obtained when the widthS of all of the openings was 4 μm.

In this case as well, it was understood that even transmittancedistribution could be obtained over the entire region as is the casewith the result of FIG. 8.

FIG. 11 illustrates the maximum luminance obtained by changing theapplied voltage in the simulation condition of FIG. 10.

In this case as well, it was understood that the maximum luminance couldbe improved by setting the width of the opening positioned on theoutermost part to be smaller than that of other openings, as is the casewith the result of FIG. 9.

As described above, according to the liquid crystal device 1 of theembodiment, the width of the opening 23 a positioned on the outermostpart in the common electrode 21 of each sub pixel is set to be smallerthan the width of other openings 23 b. As a result, evenness of lighttransmittance in the sub pixel is improved and unevenness in brightnessin the sub pixel can be reduced. Accordingly, a liquid crystal devicewhich has a superior visual angle property and can perform brightdisplay can be realized. Further, the width S1 [μm] of the opening 23 apositioned on the outermost part in the sub pixel and the width S2 [μm]of the rest of the openings 23 b are set to satisfy S2−S1≧0.5, enablingstable manufacturing in the manufacturing process and being able tosecurely provide advantages of the embodiment.

Another Embodiment

Another embodiment will now be described with reference to FIGS. 12 and13.

The basic configuration of a liquid crystal device of the otherembodiment is same as that of the above described embodiment except forthe electrode configuration.

FIG. 12 is a plan view showing a pixel constituting a display unit ofthe liquid crystal device of the other embodiment. FIG. 13 is asectional view taken along XIII-XIII line of FIG. 12. In FIGS. 12 and13, configuration elements common to those of FIGS. 4 and 5 are giventhe same reference characters and the description thereof is omitted.

In a liquid crystal device 61 of the other embodiment, a positionalrelationship of upper and lower electrodes is opposite to that in theembodiment described first, such that a common electrode 62 is formed onthe lower layer side and a pixel electrode 63 is formed on the upperlayer side as shown in FIG. 13. Specifically, the common electrode 62 isformed on the second interlayer insulation film 36 and the thirdinterlayer insulation film 37 is formed to cover the common electrode62. The pixel electrode 63 having a plurality of openings 65 is formedon the third interlayer insulation film 37. A point that a relayelectrode 25 electrically connected with the drain region of the TFT 14is provided is same as that of the embodiment described first. However,in the other embodiment, the pixel electrode 63 which is positioned onthe uppermost layer of the TFT array substrate 2 is electricallyconnected with the relay electrode 25 through a pixel electrode contacthole 64 which penetrates the third interlayer insulation film 37 and thesecond interlayer insulation film 36.

In the case of the other embodiment, the common electrode 62 is providedover all of the sub pixels and thus the common electrode 62 is notdivided for every sub pixel unlike the embodiment described first.Therefore, a common electrode line 22 in the embodiment described firstis not provided in the other embodiment as shown in FIG. 12. In order toprevent an occurrence of short-circuiting between the pixel electrode 63and the common electrode 62 in a part of the pixel electrode contacthole 64, an opening is formed on a part corresponding to the pixelelectrode contact hole 64 and a part around the part corresponding tothe pixel electrode contact hole 64, in the common electrode 62. Onlythese are the different points as a plane pattern of the sub pixel.

As a feature of the other embodiment, a plurality of long and thinopenings 65 are formed on the pixel electrode 63 in each sub pixelregion in the extending direction of the scanning line 16 with apredetermined interval, as shown in FIG. 12. Further, each of theopenings 65 extends in approximately parallel with the extendingdirection of the data line 15 and the plurality of openings 65 arearranged in approximately parallel with each other. By providing theplurality of openings 65 to the pixel electrode 63, the pixel electrode63 obtains a plurality of long and thin electrode parts 63 a and 63 b.Among the plurality of electrode parts 63 a and 63 b, the width(dimension in the short-side direction), in the alignment direction ofthe electrode parts 63 a and 63 b (extending direction of the scanningline), of the electrode part 63 a which is positioned on the outermostside is set to be smaller than the width (dimension in the short-sidedirection), in the alignment direction, of the electrode parts 63 bother than the electrode part 63 a.

In the case of the other embodiment, when the width of the electrodepart 63 a positioned on the outermost side is set to be L1 [μm] and thewidth of the rest of the electrode parts 63 b is set to be L2 [μm],L2−L1≧0.5 is satisfied. Specifically, the width L1 of the electrode part63 a positioned on the outermost part is 3 μm and the width L2 of therest of the electrode parts 63 b is 3.5 μm, for example. Further, thewidth S of the openings 65 is 4.5 μm and is constant.

In the embodiment described first, when the first electrode (lower layerside electrode) is set to be the pixel electrode, and the secondelectrode (upper layer side electrode) is set to be the commonelectrode, the width of the opening positioned on the outermost part ofthe common electrode in each sub pixel is set to be smaller than thewidth of other openings. On the other hand, in a case where the firstelectrode (lower layer side electrode) is set to be the common electrode62 and the second electrode (upper layer side electrode) is set to bethe pixel electrode 63 as the other embodiment, such configuration thatthe width of the electrode part 63 a positioned on the outermost part ofthe pixel electrode 63 in each sub pixel is set to be smaller than thewidth of the rest of the electrode parts 63 b is considered equivalentto the configuration of the embodiment described first. Accordingly, bysetting the width of the electrode part 63 a positioned on the outermostpart of the pixel electrode 63 in each sub pixel to be smaller than thewidth of the rest of the electrode parts 63 b, evenness of lighttransmittance in the sub pixel is improved and unevenness in brightnessin the sub pixel can be reduced. Thus, the same advantageous effect asthat of the embodiment described first can be obtained in the otherembodiment.

Electronic Apparatus

An electronic apparatus according to sill another embodiment will now bedescribed.

The electronic apparatus of the embodiment is an example to which theliquid crystal device of the embodiments described above is applied to aliquid crystal display unit of a mobile phone.

FIG. 14 is a perspective view showing the configuration of a mobilephone. As shown in FIG. 14, this mobile phone 720 includes a liquidcrystal display unit 724, in which the liquid crystal device of theabove described embodiments is employed, as well as a plurality ofoperation buttons 721, an ear piece 722, and a mouthpiece 723.

According to the embodiment, an electronic apparatus which can performbright liquid crystal display can be provided because it includes theliquid crystal device of the above described embodiments.

The technical scope is not limited to the above described embodiments,but various alterations can be made within the scope. For example, theabove described embodiments show the opening which is surrounded by theelectrode so as to have a closed shape, as the example of the openingformed in the second electrode. However, the opening may have a shape ofwhich one end is opened. That is, the second electrode may have acomb-teeth shape. Further, in the example of the above describedembodiments, the extending direction of the opening is parallel with theextending direction of the data line (the longitudinal direction inFIGS. 4 and 12). However, the extending direction of the opening may beparallel with the extending direction of the scanning line (the lateraldirection in FIGS. 4 and 12). In addition, as for specificconfigurations of the respective constituent elements constituting theliquid crystal device, not only the configuration shown in the abovedescribed embodiments but also the configuration which is arbitrarilyaltered may be employed.

It should be understood that various changes and modifications to thepresently preferred embodiments described herein will be apparent tothose skilled in the art. Such changes and modifications can be madewithout departing from the spirit and scope and without diminishing itsintended advantages. It is therefore intended that such changes andmodifications be covered by the appended claims.

The application is claimed as follows:
 1. A liquid crystal device,comprising: a pair of substrates composed of an element substrate and acounter substrate; and a liquid crystal layer that is held between thepair of substrates; a data line and a scanning line that are provided onthe element substrate in a manner to be orthogonal to each other; aplurality of pixels, which include a switching element that iselectrically connected to the data line and the scanning line, arrangedin matrix; a first electrode and a second electrode that are provided onthe element substrate, the second electrode applying an electric fieldgenerated between the second electrode and the first electrode to theliquid crystal layer, wherein an image signal potential from the dataline is supplied to the first electrode via the switching element, acommon potential is supplied to the second electrode, the secondelectrode includes a plurality of openings that extend parallel to eachother, the openings extend in an extending direction that is parallel tothe data line and are aligned in an alignment direction that is parallelto the scanning line, each of the plurality of openings has a constantwidth and extends in a straight line, the openings include: outermostopenings that are positioned on an outermost side in the alignmentdirection in an area corresponding to each pixel, each of the outermostopenings having a first width; and middle openings that are the openingsother than the outermost openings, each of the middle openings has asecond width, the first width is smaller than the second width at thesame corresponding position in the extending direction, and theoutermost openings overlap the first electrode in planar view.
 2. Theliquid crystal device according to claim 1, wherein when the first widthis set to be S1 [μm] and the second width is set to be S2 [μm],S2−S1≧0.5 is satisfied.
 3. An electronic apparatus, including: liquidcrystal device according to claim 1 as a display unit.
 4. The liquidcrystal device according to claim 1, wherein an area of each of theoutermost openings is smaller than an area of each of the middleopenings.
 5. The liquid crystal device according to claim 1, wherein thefirst electrode is disposed to cover an area corresponding to eachpixel.
 6. The liquid crystal device according to claim 1, wherein thesecond electrode is a solid-type common electrode disposed to coverareas corresponding to all pixels.
 7. The liquid crystal deviceaccording to claim 1, wherein the second electrode is divided into areascorresponding to areas of each pixel.